ISOLATION OF THE BACILLUS 



375 



pares the colonies in gelatin plates to those of the b. subtilis. 



They consist of a thick 



centre with shoots radi- H^^w 



ating out on all sides. 



They liquefy the gelatin 



more slowly than the b. 



subtilis. This method 



of isolation is not always 



successful, partly because 



along with the tetanus 



bacilli, both in its 



natural habitats outside 



the body and in the pus 



of wounds, other spore- 

 forming obligatory and 



facultative anaerobes oc- 



cur, which grow faster 



than thetetanus bacillus, ^ 126 ._ Spiral composed of numerous 



and thus overgrow it. twisted flagella of the tetanus bacillus. 



(2) If in any dis- Stained by Rd. Muir's method. x 1000. 



charge the spore-bearing 



tetanus bacilli be seen on microscopic examination, then a 



method of isolation 

 based on the same prin- 

 ciple as the last may 

 be adopted. Inocula- 

 tions with the suspected 

 material are made in 

 half a dozen deep tubes 

 of glucose agar, previ- 

 ously melted and kept at 

 a temperature of 100 e 

 C. After inoculation 

 they are again placed in 

 boiling water and kept 

 for varying times, say 

 for half a minute, for 

 one, three, four, five, 



FIG. 127. Tetanus bacilli ; some of which and six minutes respect- 

 possess spores. From a culture in glucose i ve } v They are then 

 agar, incubated for three days at 37 C. > > -, -, 



Stained with carbol-fuchsin. x 1000. Ponged in cold water 



till cool, and thereafter 



placed in the incubator at 37 C., in the hope that in one 



or other of the tubes all the organisms present will have been 



